Sudden spike in water pressure

[newbie23]

My hot water tank T&P valve broke and water started leaking. I called a local plumber. He replaced T&P valve and said it is a good practice to replace PRV too. My PRV is only 2 years old. But I went ahead and changed it also.

All looked ok for 2 weeks. Then I started noticing high water pressure during random times in random faucets. like Few times in kitchen faucet and few times in bathroom faucet. So attached water pressure test gauge to my outdoor water outlet. This outlet is connected to the line after the PRV. The pressure showed 50 PSI both red and black needle. I let it sit and next day i see the black stayed at 50 but the red moved to 140. That means at sometime the water pressure increased to 140 . I am not sure what is causing this issue. I am attaching the pics.

Anyone help me with the diagonoses? I called the plumber he said all looks fine. But my mind keeps worrying about this sudden increase in water pressure and what happens if there is a water pipe burst.

 

[Twowaxhack]

Check your thermal expansion tank

 

[newbie23]

there is no expansion tank for my hot water tank. It is almost 15 yrs old.

 

[Twowaxhack]

there is no expansion tank for my hot water tank. It is almost 15 yrs old.

That might be your issue.

 

[newbie23]

That might be your issue.

Thanks for the response. The tank is like 19 years old without expansion tank May I please know why the problem Is happening now?

My next question if it is due to aging of the water heater then do you recommend just adding expansion tank or installing new water heater?

 

[MASTRPLUMB]

THE CITY PROBLY RAISED THE PRESSURE

 

[MASTRPLUMB]

GET A WATTS GOV. 80 BALLCOCK IT WILL RELEASE THERMAL EXPANSION

 

[Twowaxhack]

You could test for thermal expansion. Google it and it’ll explain how to conduct the test.

Your system may not have always been closed. A system can become closed several ways. So a closed system or a system with pressure above the desired level would require expansion control.

 

[RS]

It sounds like your new PRV has a check valve in that you didn't have before, so now you need a expansion tank by your water heater.

 

[newbie23]

It sounds like your new PRV has a check valve in that you didn't have before, so now you need a expansion tank by your water heater.

Is there a way to check?

 

[Twowaxhack]

Is there a way to check?

Read post number 8 of this thread.

 

[wpns]

Only slighty OT: Is there a pressure guage like the above picture but that reads min _and_ max pressure since reset?

 

[newbie23]

Only slighty OT: Is there a pressure guage like the above picture but that reads min _and_ max pressure since reset?

Red needles is the max it went at during the 2 day period. Black needle is the current pressure. I don’t know if there one minimum with minimum.

 

[Twowaxhack]

The problem with those type gauges is that a solenoid valve appliance or some single lever faucets can cause the spike.

 

[RS]

It should say so on the specifications. Why not just put the old PRV back in? They should last way more than a few years.

 

[newbie23]

It should say so on the specifications. Why not just put the old PRV back in? They should last way more than a few years.

The PRV is installed two months back and the old PRV he took it with him. The one installed is WATTS LF25AUBZ3 and specification is here. I can't quite understand if it has built in check valve.

 

[wpns]

That doesn’t have a check valve, it has a bypass to allow excess pressure from the house back into the main.

BUT

Only when the pressure in the house exceeds the main pressure.

Any idea what your mains pressure is?

 

[newbie23]

No. I don’t know the pressure in the main line.

 

[MicEd69]

The bypass feature on this model does not work until the pressure reaches 150 psi. So, as Twowaxhack indicated, you should install a thermal expansion tank to resolve this issue.

 

[wpns]

Then you either need to measure it, or follow the other help in this thread.